Unsaturated Iron Binding Capacity
The unused iron-carrying capacity of transferrin.
| Typical reference range | 111–343 ug/dL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
UIBC measures how much additional iron transferrin could bind. Serum iron plus UIBC equals TIBC.
Why it matters
Labs often measure UIBC directly and calculate TIBC from it. High values indicate an empty transport system typical of iron deficiency.
What a high result can mean
High UIBC suggests iron deficiency or increased transferrin from pregnancy or estrogen.
What a low result can mean
Low UIBC suggests iron overload, high recent iron intake, or reduced transferrin from inflammation or liver disease.
What affects the result
Same timing considerations as serum iron. Interpret with ferritin and transferrin saturation.
Units and conversion
Usually reported in ug/dL.
- From umol/L: multiply by 5.585 to get ug/dL
Also called on lab reports
UIBC, Unsaturated Iron-Binding Capacity, Unsat. Iron Binding Capacity
Related tests: Iron Status
This page is educational and does not replace advice from a healthcare professional.